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Life on Mars?
This simple question has captivated millions of minds since the days of astronomer Percival Lowell. We're still no closer to a definitive answer. That doesn't mean we've stopped trying to answer it though. Since the days of the Viking landers, spacecraft have been carrying out tests for life processes, analyzing Martian soil for traces of water and looking for the release of gases such as carbon dioxide, methane and oxygen that might result from the activities of bacteria. These tests have seemed to show that the Martian soil was chemically active, but not biologically active.
It's possible that we need to revisit our idea of Martian life. Rather than egg-headed green aliens whizzing around in UFOs, we may have to be content with the possibility of much smaller organisms, like bacteria. Biologists have unearthed bacteria living in inhospitable environments on Earth, such as Antarctica, so they theorize that life also could exist in the cold desert conditions of Mars.
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The guy on the left might be what you're picturing when you think about life on Mars, but the bacteria on the right are the more realistic possibility.
In fact, researchers discovered a species of bacteria that had been lying dormant for 120,000 years two miles below Greenland's ice [source: Heinrichs]. After melting the surrounding ice and filtering out larger bacteria, Chryseobacterium greenlandensis awoke from its frozen slumber and started multiplying. Scientists are hoping for a similar discovery within the red planet's polar ice caps. If that doesn't sound too exciting to you, remember that bacteria was the first life form here on Earth.
If you're not too picky about where the life originates, we may see life on Mars, compliments of our spacecraft. Although the U.S. and other countries involved in space exploration have pledged to refrain from contaminating celestial bodies, bacteria such as E. coli and potentially even Legionella have been found in the International Space Station [source: Society for General Microbiology]. The Phoenix lander undoubtedly provided a ride to hundreds of thousands of microbes, although NASA states that the lander must not harbor more than 300,000 bacterial spores total, and it took several precautions to ensure that the lander's robotic arm was clean [source: NASA].
Photo courtesy NASA
Nevertheless, the prospect of bacteria in space isn't quite as exciting as those Martians. But if you're a believer, don't lose hope. The final answer to the question of life on Mars, as well as the answers to other Martian mysteries, may require humans to explore the red planet in person.
For more Mars madness, browse the stories and links on the next page.